唇齿 (chúnchǐ): lips and teeth

Meanings

1 lips and teeth
2 (figurative) close partners; mutually dependent parties

Characters

唇

Examples

两国关系如同唇齿，不可分离。

Liǎng guó guānxi rútóng chúnchǐ, bùkě fēnlí.

The two countries are like lips and teeth — inseparable.

他们俩是唇齿相依的好朋友。

Tāmen liǎ shì chúnchǐ xiāngyī de hǎo péngyǒu.

The two of them are close friends who depend on each other completely.

Tips

history

From the chengyu 唇亡齿寒 (chúnwáng chǐhán, 'when the lips are gone, the teeth feel cold'), recorded in 《左传》. The Spring & Autumn parable — Jin asked Yu to lend passage to attack Guo; Gong Zhiqi warned that without Guo, Yu was next. Yu refused the warning, Guo fell, then Yu fell. Hence 'lips and teeth' = mutual survival.